The present invention relates to an illumination device for generating a light strip along a predetermined distance on a component
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
In order to allow a person to orient themselves also inside the motor vehicle in darkness individual components for example a cup holder or a loudspeaker can be illuminated from their interior with a light source. The person can then recognize where the functional element is located in the interior without the entire interior having to be illuminated. The above mentioned illumination device allows to distribute the light of a light source along a contour of the respective functional element so that the contour is recognizable in the dark as bright strip. Typically such an illumination device is used for a circumferential illumination, i.e. in this case the strip has the shape of a closed band.
In order to generate a circumferential light strip, a ring shaped light conductor made of Polymethylmethacrylate (PMMA, Plexiglas) can be used into which light is coupled on both ends. The light conductor has the shape of the contour to be represented and can for example by means of a latching engagement be fixed on the component or about the component. The light emitting diodes can each be mounted in an element for coupling-in which an electric switch is located for operating the light emitting diode and by which light of the light emitting diode is focused and directed onto a coupling surface of the light conductor.
Along its longitudinal extension in the direction of extension of the contour, the light conductor has scattering centers i.e., for example indents on its outer walling or reflecting particles in its inside by which a portion of the light is respectively deflected and exits the light conductor. By this, the light of the light diodes is distributed along the distance, thereby causing the light conductor to appear evenly bright along the contour. By means of such light conductors a surface of up to 200 mm×150 mm can typically be surrounded by an evenly bright sight strip.
When a larger area is to be surrounded with a circumferential light strip, the light strip has to have an according length. This poses the problem that thermally caused changes in length of the light conductor can cause mechanical tensions in its material which can lead to hairline cracks in the material or even destruction of the light conductor. In particular, in a motor vehicle temperatures of between −40° C. to 80° C. can occur.
It would therefore be desirable and advantageous to provide an improved illumination device by means of which an evenly bright light strip can be produced along the contour of a large-surface-area functional element.